1. Field of the Invention
This invention relates to a liquid detergent which has improved fabric softening properties. The invention particularly relates to a surfactant-containing liquid detergent which also includes fatty acid dietha-nolamides prepared in part from monounsaturated fatty acids. Fabrics washed with the liquid detergent of this invention generally do not require after-treatment with known conditioners.
2. Description of Related Art
There are many known liquid detergent formulations containing relatively large amounts of fatty acid monoor diethanolamides. These ethanolamides are derived from fatty acid mixtures containing a high percentage of C.sub.12 -16 fatty acids, for example coconut oil fatty acids. While these particular alkanolamides increase the detergents' cleaning and foaming power and improve its compatibility with the skin, the detergents themselves provide no conditioning effect to the laundered fabrics. Examples of these detergents include those disclosed in U.S. Pat. Nos. 3,697,451; 4,153,570; 4,298,492; 4,452,717; 2,861,956 and 2,943,058; UK Pat. No. 1,600,018 and German Patent Application No. 1,047,973.
The addition of quaternary ammonium salts to anionic surfactant-containing detergents has been proposed in order to obtain a detergent which simultaneously provides a conditioning effect. Typically, these quaternary ammonium salts contain relatively long chain fatty acid or fatty alkyl residues. However, since the anionic surfactants generally are incompatible with these quaternary ammonium salts or react with the salts to form inactive electro-neutral salts, the desired conditioning effect generally is not obtained.
It is also known that certain stearic acid derivatives of alkylolamides may be used as softening agents in treating textiles (Soap and Chemical Specialities, November 1958, pages 48 to 50). However, problems involving the behavior of these compounds when used in surfactant-containing detergents are not addressed. In fact, it has been found that storage stable liquid surfactant-containing detergents cannot be prepared containing an effective amount of these stearic acid derivatives.
The detergents of the present invention, described in detail hereinafter, overcome the above-mentioned disadvantages.